Fine needle aspiration (FNA)

A fine needle aspiration (FNA) is a type of biopsy. It uses a very thin needle and syringe to remove a sample of cells, tissue or fluid from an abnormal area or lump in the body. The sample is then examined under a microscope. FNA is also called fine needle aspiration biopsy, or fine needle biopsy.

Why a fine needle aspiration is done

Doctors use an FNA to check an abnormal area or lump for cancer or other diseases. It may be done when the doctor can feel or touch a lump (it is palpable). It may also be done if imaging tests show an abnormal growth or area. Doctors often use an FNA to collect samples from lumps in the thyroid or breast or from lymph nodes.

How a fine needle aspiration is done

You may have an FNA in a doctor’s office or as an outpatient in a hospital. You usually don’t need to do any special preparation for the test. An FNA does not usually take very long to complete.

You are usually lying down for the procedure. The healthcare team will clean the area where the needle will go in. They may use a local anesthetic to numb the area.

Sometimes doctors use an imaging test, such as an ultrasound or CT scan, to guide the needle into the specific area they want to check. This is often done when the area is deep in the body, very small or can’t be felt.

The doctor inserts a very thin needle through the skin and into the area being examined. The needle is usually attached to a syringe. The doctor slowly draws, or aspirates, cells, tissue or fluid through the needle and into the syringe. You may feel some pressure or discomfort during the FNA, but it’s not usually painful.

Sometimes doctors need to do more than one FNA to collect samples from different areas to make a diagnosis. New needles and syringes are used for each FNA.

After the doctor removes the needle, a bandage is put over the area where the needle was inserted. The cells, tissue or fluid collected (called the biopsy sample) is sent to a lab to be examined under a microscope.

Side effects

An FNA may cause:

discomfort or soreness

bleeding

infection

damage to nearby structures

Talk to your healthcare team if you have any of these side effects.

After a fine needle aspiration

A pathologist (a doctor who specializes in the causes and nature of disease) will send a report to your doctor with the results of the FNA. An FNA may show that:

the cells in the biopsy sample are normal

the lump or area tested is non-cancerous (such as a breast cyst or benign thyroid nodule)

there is an infection

there are precancerous or abnormal cells that may become cancer if not treated

there are cancer cells in the area tested

Sometimes the pathologist may note that the FNA did not collect enough tissue or fluid to make a diagnosis. When this happens, the doctor will need to do another FNA.

Ask your doctor when you will find out the results of the FNA. Your doctor will talk to you about the results and decide if more tests, procedures, follow-up care or treatment is needed.

Special considerations for children

Preparing children before a test or procedure can lower anxiety, increase cooperation and help them develop coping skills. Preparation includes explaining what will happen during the test, including what they will see, feel and hear.

The preparation for an FNA depends on the age and experience of the child. Your child’s doctor or healthcare team will tell you if your child needs to stop eating and drinking before the FNA. Your child may be given medicine to make them sleepy during the procedure.